3-[3,3,3-trimethyl-1,1-bis[(trimethylsilyl)oxy]disiloxanyl]propyl methacrylate

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988-12-23 to 1989-02-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-[3,3,3-trimethyl-1,1-bis[(trimethylsilyl)oxy]disiloxanyl]propyl methacrylate

EC Number:

241-165-0

EC Name:

3-[3,3,3-trimethyl-1,1-bis[(trimethylsilyl)oxy]disiloxanyl]propyl methacrylate

Cas Number:

17096-07-0

Molecular formula:

C16H38O5Si4

IUPAC Name:

3-{2,2,6,6-tetramethyl-4-[(trimethylsilyl)oxy]-3,5-dioxa-2,4,6-trisilaheptan-4-yl}propyl 2-methylprop-2-enoate

Test material form:

other: liquid

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Breeding Centre for Laboratory Animals, Germany
- Age at study initiation: 4 weeks old
- Weight at study initiation: 100.2 to 137.2 g for males and 83.6 to 109.1 for females
- Fasting period before study:
- Housing: housed in group of 5 (males and females separated) in suspended, stainless steel cages
- Diet: open-formula diet for rats, mice and hamsters, ad libitum
- Water: tap water, ad libitum
- Acclimation period: 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 23 °C
- Humidity (%): 40 - 60 %
- Air changes (per hr): 10/hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: Fresh dosing solutions containing the appropriate levels of test substance were prepared weekly and stored in a refrigerator at 4°C. Magnetic stirrer was used to stir the stock solution before and during administration.

VEHICLE
- Justification for use and choice of vehicle (if other than water): the test substance was found to be stable in corn oil during storage for 7 days at 5 °C. During the study, the content of the test substance in the dosing solutions was checked by analysis and found to be close to the intended value.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Prior to the toxicity study analysis of the stability of the test substance in corn oil were performed upon storage conditions for one week in a refrigerator at 5°C. During the study, the content of the test substance in each of the solutions prepared was checked by analysis. The analysis were carried out in TNO-CIVO Analysis Institute.

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily, 7 days a week

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

80 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

400 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

2 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

Main study: 5 males and 5 females per dose
Reversibility study: 5 males and females as a control group and 5 males and females treated with 2000 mg/kg bw/day.

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale:
- Rationale for selecting satellite groups: 5 male and 5 female animals treated with the highest dose 2000 mg/kg bw/day were selected as satellite group as well as the control animals.
- Post-exposure recovery period in satellite groups: 14 days

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily during the week days and once daily during the weekends
- Cage side observations included: all abnormalities, signs of ill health or reaction to treatment as well as moribund or dead animals were recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights of each rat were recorded at study initiation, then on days 4, 7, 11, 14, 18, 21, 25 and 28. During the recovery period the rats were weighed on days 35 and 42.

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on day 24
- Anaesthetic used for blood collection: No
- Animals fasted: No data
- How many animals: all animals
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on day 26 (determination of glucose levels); on day 28 blood was collected from all the animals while under ether anaesthesia
- Animals fasted: Yes; deprivation of water for 24 hours and food for 16 hours prior to blood samples collection
- How many animals: all the animals
- Parameters checked in table [No.1] were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: on days 25-26
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes; deprivation of water for 24 hours and food for 16 hours.
- Parameters checked in table [No.1] were examined.

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 2). The animals from the main study were sacrificed on day 28. The animals from the reversibility study were sacrificed on day 42 of the study period.
HISTOPATHOLOGY: Yes (see table 2)

Statistics:

- One-way analysis of co-variance followed by Dunnett's test were used for body weights evaluation
- ANOVA followed by Dunnett's test were used for evaluation of red blood cells, total white blood cells, absolute number of neutrophils and lymphocytes, clinical chemistry values, urinary volume and density and organ weights.
- Mann-Whitney U-test was used for evaluation of differential white blood cell count
- Fisher's test was used for evaluation of incidence of histopathologic changes
- t-test was used for evaluation of parameters during the recovery period

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

Focal alopecia was observed in 4/5 males and 3/5 females treated with 2000 mg/kg bw/day, but was considered a normal finding for rats at this strain and age. 1/5 male treated with 2000 mg/kg bw/day showed emaciation, weakness, ataxia, pallor and a low body temperature. 1/5 control female showed emaciation, cyanosis, encrustrations around the nose and porphyrin accumulation along the eye lids.

Mortality:

no mortality observed

Description (incidence):

1/5 males of the mid dose group were found dead on day 21 of the study. The remaining rats survived until their scheduled sacrifice.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No statistically significant differences in body weights between the test group and the control group. For unknown reasons, growth of males of the control group was markedly retarded in the last week of the recovery period.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

no effects observed

Description (incidence and severity):

No substance-related influence on food intake or food efficiency.

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

Throughout the treatment period, water intake was clearly increased in males of the top-dose group, and to a lesser extent in males of the mid-dose group and in females of the top-dose group. In the recovery period top-dose rats consumed about as much water as did control rats.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No statistically significant changes in red blood cell variables were noted at the end of the treatment period except for a slight decrease in mean corpuscular haemoglobin in low and mid dose females. This change was considered to be arithmetic rather than toxicological, because there were no changes in the measured red blood cell variables.
Prothrombin time was decreased in the high dose rats of both sexes and in males of mid dose. No changes were noted in low dose rats. At the end of the recovery period high dose rats still exhibited decreased prothrombin time, but statistical significance was reached only in males.
Differential white blood cell counts showed an increased number of lymphocytes, resulting in an increased total white blood cell count, in top dose males towards the end of treatment. ncreased number of lymphocytes, resulting in an increased total white blood cell count, in high dose males was noted towards the end of the treatment period. Increased counts of lymphocytes and total white blood cells in the low dose group in males were not considered treatment-related since elevated counts occurred in only one animal of this group.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Increased alanine aminotransferase was observed in the highest dose rats of both sexes. Increased aspartate aminotransferase activities was observed in the highest dose rats of both sexes. Statistical difference with control group was observed in males only.
Decreased gamma glutamyl transferase activity in all dosed groups in both sexes. Statistical difference with control group was observed in males only.
Decreased albumin concentrations at all dosed groups in males.
Decreased total protein concentration in low dose males. Such change was not observed in mid and top dose males, the change in low dose males was considered to be irrelevant to treatment.
Increased potassium concentration in low and high dose males.
Changes in aspartate aminotransferase and gamma glutamyl transferase activities were statistically significant in males only. At the end of the recovery period alanine aminotransferase and aspartate aminotransferase activities were still increased most of high dose males and 2/5 females with differences with control being larger than at the end of the treatment. Other changes observed after recovery were: decreased albumin concentration and albumin to globulin ratio in both sexes, increased gamma glutamyl transferase activity in females and decreased plasma sodium concentration in males.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment-related changed to urinary volume or density.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

No statistically-significant changes in absolute organ weights. Relative organ weights revealed an increased liver weight in the mid and high dose animals from both sexes. This change persisted till the end of the recovery period. Relative testes weight in males and relative brain weight in females were significantly increased at termination of recovery period.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Clear fluid and fat droplets were observed in the thoracic cavity of the mid dose male that was found dead on day 21. The cause of death was probably trauma due to the gavage treatment.
Necropsy at the end of the 14-day recovery period revealed treatment-related gross changes of the liver, characterised by yellow discolouration and the presence of yellow spots.
Adrenals, heart, kidneys and spleen did not show any treatment-related changes. The changes observed in these organs were common findings in rats of this strain and age and they were equally distributed among test and control animals.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Treatment-related hepatic changes characterised by multifocal aggregates of RES cells and necrotic hepatocytes in mid and high dose groups and were more pronounced in males than females. The multifocal hepatocellular swelling observed in males of the top dose group was also considered to be treatment-related. The other changes observed in the liver were either equally distributed among test and control groups or were observed in one animal only, therefore not considered to be treatment-related.
At the end of the 14-day recovery period, microscopic liver lesions related to hepatotoxicity were observed. These lesions included: multifocal aggregates of RES cells and necrotic hepatocytes; single cell necrosis; areas showing hepatocellular necrosis frequently accompanied by fibrosis; hepatocellular vacuolation; multifocal hepatocellular swelling. Liver damages were more severe after the recovery period than after the 28-day treatment period.

Histopathological findings: neoplastic:

not examined

Effect levels

Dose descriptor:

NOAEL

Effect level:

80 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical biochemistry

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table 3: Summary of microscopic changes observed at the end of the treatment period

Changes	Incidence of lesions (numeric)
	Males				Females
	control	Low dose	Mid-dose	Top-dose	Control	Low-dose	Mid-dose	Top-dose
Adrenals: Diffuse cortical vacuolation Focal cortical vacuolation Medullary sinusoidal dilatation Zona reticularis sinusoidal dilatation	(5) 1 2 0   0			(5) 0 2 1   1	(5) 0 0 0   0			(5) 0 0 0   0
Heart: Pericarditis	(5) 0			(5) 0	(5) 1			(5) 0
Kidneys: Focal tubular nephrosis Focal corticomedullary mineralisation	(5) 1 0			(5) 1 0	(5) 2 1			(5) 1 1
Liver: Focal hepatocellular swelling Multifocal hepatocellular swelling Focal aggregates of RES cells and necrotic hepatocytes Slight Moderate Severe Very severe Total incidence for score expanded findings Focal mononuclear-cell infiltrate Focal single cell necrosis Focal hepatocellular necrosis Multifocal hepatocellular necrosis	(5) 0 0   5   0 0 0 0 0   0   0 0 0	(5) 0 0   5   0 0 0 0 0   0   0 0 0	(5) 0 0   1*   3 0 0 0 3   0   0 0 0	(5) 2 3   2   0 0 2 1 3   0   2 0 0	(5) 0 0   4   0 0 0 0 0   0   1 0 0	(5) 0 0   3   0 0 0 0 0   1   0 0 0	(5) 0 0   4   0 1 0 0 1   0   0 1 0	(5) 0 0   2   0 1 1 1 3   0   0 0 1
Spleen: Extra medullary hematopoiesis	(5) 0			(5) 0	(5) 1			(5) 0

Figures in brackets represent the number of animals from which tissue was examined microscopically

Blansk indicate the tissues were not examined

* significance of differences between treatment and control group (p< 0.05)

Table 4: Summary of microscopic changes observed after 14 -day recovery period

Changes	Incidence of lesions (numeric)
	Males				Females
	control	Low dose	Mid-dose	Top-dose	Control	Low-dose	Mid-dose	Top-dose
Liver: Multifocal hepatocellular swelling   Focal aggregates of RES cells and necrotic hepatocytes   Very slight Slight Moderate Total incidence for score expanded findings   Multifocal aggregates of RES cells and necrotic hepatocytes Moderate Severe Very severe Total incidence for score expanded findings   Multifocal single cell necrosis   Multifocal hepatocellular necrosis   Focal hepatocellular necrosis   Slight Moderate Severe Very severe Total incidence for wscore expanded finding Diffuse hepatocellular vacuolation Multifocal hepatocellular vacuolation Focal hepatocellular vacuolation Focal fibrosis	(5) 0 4 1 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	(5)	(5)	(5) 4* 0* 0 0 0** 0 2 3 0** 5** 5** 0 1 1 2 4* 1 2 2 3	(5) 0 2 2 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	(5)	(5)	(5) 1 0 0 1 1 0 3 0 1 4* 0 1 1 0 2 0 3 0 3 2 2

Figures in brackets represent the number of animals from which tissue was examined microscopically

Blanks indicate the tissues were not examined

* significance of differences between treatment and control group (p< 0.05)

** significance of differences between treatment and control group (p< 0.01)

Applicant's summary and conclusion

Conclusions:

In the 28-day oral repeated dose toxicity study with 3-[3,3,3-trimethyl-1,1-bis[(trimethylsilyl)oxy]disiloxanyl]propyl methacrylate, the study author concluded a 'no toxic effect level of <80 mg/kg bw/day in rats based on adverse effects on the liver seen in middle and high dose animals, which increased in severity during the post-exposure recovery period in the highest dose group. But it is the opinion of the EPSR author that the NOAEL is 80 mg/kg bw/day based on the clinical biochemistry findings in low dose males not being associated with any organ weight changes, gross pathology or microscopic findings. These effects are considered to be not adverse as statistical significance is seen in males only. Clear toxicity effects are observed in liver at middle and high dose animals.